Code Analysis error Could not load file or assembly 'System.Net.Http, Version=2.0.0.0 in MVC4 Web API

28
votes

this problem is exactly the same as this post http://forums.asp.net/t/1807797.aspx/1?System+Net+Http+is+not+found and this one on StackOverflow

I have all the latest RTM bits, Started a new MVC 4 in .Net 4.5, added the WebAPI nuget package and now my code analysis fails with the same error as reported in the above link.

CA0058 Error Running Code Analysis CA0058 : The referenced assembly 'System.Net.Http, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' could not be found. This assembly is required for analysis and was referenced by: C:\Projects\InHouse\TimeRecorder\StopGap\TimeRec\bin\TimeRec.dll, C:\Projects\InHouse\TimeRecorder\StopGap\packages\Microsoft.AspNet.WebApi.Core.4.0.20710.0\lib\net40\System.Web.Http.dll. [Errors and Warnings] - (Global)

From what I can find this seemed to happen with the RC versions because there was a conflict between the .NET 4.5 framework System.Net.Http and the WebApi's version of the System.Net.Http.

The other answers on the StackOverflow response talk about downgrading from .Net 4.5 to 4.0, for obvious reasons, this is not my preferred solution!

4
asp.net-web-api
I'm experiencing this problem as well, have you found a solution? – Lari Tuomisto
I can't repro the issue with VS 2012 RTM bits. One thing strange to me is that every MVC 4 templates in MVC4 already having web api package installed. Why do you have to install the package again? – Hongye Sun
Starting in Visual Studio 2012, a better workaround is: stackoverflow.com/questions/17298281/…. – David Kean

4 Answers

71
votes

Try the following:

  1. Depending on your Visual Studio edition navigate to:
    • VS 2010:
      %ProgramFiles(x86)%\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\FxCop
    • VS 2012:
      %ProgramFiles(x86)%\Microsoft Visual Studio 11.0\Team Tools\Static Analysis Tools\FxCop
  2. Open FxCopCmd.exe.config and change AssemblyReferenceResolveMode from StrongName to StrongNameIgnoringVersion.
  3. Save the change and rebuild your project.
5
votes

From Visual Studio 2012 and higher, instead of modifying your installation files, use the workaround specified here: Using Microsoft.Bcl.Async with Code Analysis causes errors.

2
votes

I have had the same problem (couldn't build locally and remotely on azure). This workaround helped me: http://connect.microsoft.com/VisualStudio/feedback/details/760208/nuget-package-for-asp-net-mvc-4-web-api-does-not-reference-correct-net-4-5-assemblies#

here is the part you need:

Copy the System.Net.Http.dll and System.Net.Http.xml files contained in the packages\Microsoft.Net.Http.2.0.20710.0\lib\net40 directory to the packages\Microsoft.AspNet.WebApi.Core.4.0.20710.0\lib\net40 directory. Since the missing System.Net.Http.dll assembly is now in the same location as the referenced System.Web.Http.dll assembly, the code analysis can now properly resolve the conflicting System.Net.Http assembly.

0
votes

The issue is caused because you have a dependency on a newer version of System.Net.Http, than that required by one of the other assemblies referenced.

The correct way to resolve this issue is to add dependentAssembly redirects to the app.config of offending projects. The accepted answer of disabling the errors just masks an underlying problem.

Add the following to the runtime section of app.config to remap the old version that can't be resolved to the version referenced in your project. The version numbers should obviously be updated to correspond to your situation.

<runtime>
  <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
    <dependentAssembly>
      <assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
      <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
    </dependentAssembly>
  </assemblyBinding>
</runtime>